Yesterday Car Toys replaced my stock head unit with an Alpine iDA-X305.

I decided against paying more for the iDA-X100M. It's too silver for my taste. The trim ring is white. The 305 was already in stock.



The install started off as planned. The tech pulled the old unit, ran the iPod cable to the storage compartment in the center console, and connected the new unit to the existing cable harness using a Scosche adapter.

Then it got interesting. Even though the stock amplifier has 4-channel inputs (L+R door, L+R subs), the stock cable harness and radio are two-channel. The two are split into four somewhere before the amp inputs. {stock-amp-4-channels-crossfire-audio_diagram.pdf}

I guess that's the reason many of y'all have added capacitors to the door woofers. Lacking a crossover, they rattle the doors like crazy below 110Hz and distort the upper bass.

The technician claimed the stock amp was under the passenger seat and asked for another $80 to run the wires. I agreed even though I read here that it's under the passenger foot board. Turns out the forum is right. A seat pulled for no reason. I guess I should have argued. Regardless it took him much longer to splice the wires than pull/replace the seat.

After all was done, the front outputs connected to the amp door inputs and the sub outs to the amp rear inputs, the technician complained that it sounded no different than just splitting the fronts.

Of course it didn't. He didn't know to enable the high-pass filter on the head unit. I set it at 160 Hz. That gave the smoothest frequency response and insignificant rumble from the door speakers.

Music with deep bass now sounds fantastic. The subs behind the seat put out credible bass down to 25Hz! I could never hear it over the door rumble.

A just wanted to add this cautionary tale for all those looking for plug in replacements for the head unit. The wiring harness is only 2-channel! You'll still have bass issues if you don't run separate wires from your head unit sub outputs to the amplifier. I think that may be why several forum members have complained after upgrading. Car Toys and other installers are more than happy to plug in the adapter and never notice much less inform you that the stock amp is capable of more.

Just a few more observations:

- The stock amp accepts 4V inputs even though many head units output 2V. This was no problem with the Alpine. Max volume sounds non-distorted and loud enough.

- Using a test CD these settings sounded accurate to my ears:
High-pass: 160Hz
Subwoofer output: max
Treble: flat
Bass: flat

- The non-matte LCD screen reflects glare at certain angles.

- The iPod controls are quicker than most. It still takes a half-second to skip a song.

- The stock amp and six speakers perform well above average. They are just hobbled by the cheap head unit.

 

The stock amp will take a 12 volt input, which is what the stock Becker head unit puts out. I used my JVC pre-outs, which are 5 volt. It is not nearly as loud as the Becker, but it is more than enough for me.

 

Did a X305 install myself a while ago and have been playing with the settings trying to find the sweet spot and while it sounds better than stock I'm not 100% satisfied. I think my problem is it just doesn't get quite loud enough for me (overall). I use Ipod for all input so some songs are louder/quieter than others but I find the majority are lower than I would like. I have pretty much the same settings

Sub Volume +13
High Pass - 120hz or 80.

I find the subs just don't fill in the missing mids even at 80. The sound is better than stock for sure it just isn't as warm if you will. I think this is an issue with the amp though, while setting mine up I did a test. I hooked the rears to the front pre out and the sound was the same as going through the sub pre out. Unless the speakers can only handle low frequencies (haven't checked specs but at that size I doubt it) the amp limits the output to the rear.

Overall much better than stock, just wish there was a couple more notches on the volume dial. At full it is right near the point where distortion will start to come in but it could go just a liiiiittle more.